Underground mine intelligent anchor rod self-adaptive adjusting equipment and adjusting method thereof

Abstract

The invention relates to the technical field of underground mine supporting and particularly discloses underground mine intelligent anchor rod self-adaptive adjusting equipment which comprises an outer rod, a driving assembly is arranged in the outer rod, the driving assembly comprises a driving motor, and the driving motor is fixedly arranged at one end of an inner cavity of the outer rod; one end of the driving motor is rotatably provided with a transmission screw rod, the surface of the transmission screw rod is sleeved with a thread sleeve in a threaded mode, the surface of the thread sleeve is fixedly sleeved with a transmission block, transmission plates are fixedly arranged on the two sides of the transmission block, and sliding blocks are fixedly arranged on the two sides of the transmission plates; sliding grooves matched with the sliding blocks are formed in the two sides of the inner cavity of the outer rod. By arranging the displacement sensor and the stress sensor, stress and displacement parameter data can be collected in real time, threshold value judgment can be conducted, according to the judgment result, through cooperation of the driving assembly, the supporting force is automatically adjusted, mechanical state changes of surrounding rock are adapted in time, and surrounding rock deformation is effectively controlled.

Description

Technical Field

[0001] This invention patent relates to the technical field of underground mine support, and specifically to an intelligent bolt adaptive adjustment device for underground mines and its adjustment method. Background Art

[0002] Underground mine support refers to a series of engineering measures taken during the underground mine exploitation process to maintain the stability of underground spaces such as roadways and stopes, and to ensure the safety of operating personnel and equipment.

[0003] In underground mine exploitation operations, to control the stability of surrounding rocks, bolt support technology is required. However, traditional bolts mostly have a fixed structure and cannot adapt to dynamic deformation. When the surrounding rocks are affected by mining and undergo creep and crack expansion, fixed-length bolts are prone to breakage or failure due to stress concentration. At the same time, traditional bolts rely on manual regular inspections and manual pre-tightening force adjustment, and cannot automatically adjust the support force according to the change in the mechanical state of the surrounding rocks, and cannot respond in real time to the complex and changeable geological environment, reducing the stability of the roadway. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, this invention patent provides an intelligent bolt adaptive adjustment device for underground mines and its adjustment method, which has the advantages of being able to automatically adjust the support force according to the change in the mechanical state of the surrounding rocks, etc., and solves the problem that the bolt cannot automatically adjust the support force according to the change in the mechanical state of the surrounding rocks.

[0005] An intelligent bolt adaptive adjustment device for underground mines of the present invention for invention patent, including an outer rod, a driving assembly is arranged inside the outer rod, the driving assembly includes a driving motor, the driving motor is fixedly arranged at one end of the inner cavity of the outer rod, a transmission screw is rotatably arranged at one end of the driving motor, a screw sleeve is threadedly sleeved on the surface of the transmission screw, a transmission block is fixedly sleeved on the surface of the screw sleeve, transmission plates are fixedly arranged on both sides of the transmission block, sliders are fixedly arranged on both sides of the transmission plate, and sliding grooves adapted to the sliders are respectively opened on both sides of the inner cavity of the outer rod. One ends of the two transmission plates are both fixedly provided with inner rods, diffuse reflection coatings are arranged on the surfaces of the two inner rods, displacement sensors adapted to the diffuse reflection coatings are respectively embedded on both sides of the inner cavity of the outer rod, one ends of the two inner rods are fixedly connected with a hydraulic jack, a hydraulic pump is fixedly arranged at one end of the inner cavity of the outer rod and on one side of the driving motor, an oil pipe is fixedly arranged at one end of the hydraulic pump, and one end of the oil pipe is fixedly connected with the hydraulic jack. A limiting block is movably sleeved on the surface of the oil pipe, and the limiting block is fixedly arranged in the inner cavity of the outer rod. One side of the limiting block is movably connected with one end of the transmission screw. A stress sensor is embedded and installed on the inner wall of the outer rod. A controller is fixedly arranged at one end of the inner cavity of the outer rod, and the displacement sensor, the stress sensor, the driving motor and the hydraulic pump are all electrically connected with the controller. A first ventilation pipe and a second ventilation pipe are symmetrically arranged in the inner cavity at one end of the outer rod, and a heat dissipation assembly is connected to one end of the first ventilation pipe.

[0006] An intelligent bolt adaptive adjustment device for underground mines of the present invention for invention patent, wherein a screw is arranged at one end of the outer rod, and a backing plate and an expansion bolt are respectively sleeved on the surface of the screw.

[0007] An intelligent bolt adaptive adjustment device for underground mines of the present invention for invention patent, wherein one ends of the first ventilation pipe and the second ventilation pipe both penetrate through the backing plate, and a filter screen is arranged in the inner cavity of the second ventilation pipe.

[0008] An intelligent bolt adaptive adjustment device for underground mines of the present invention for invention patent, wherein the heat dissipation assembly includes a connecting pipe, one end of the connecting pipe is fixedly connected with the first ventilation pipe, the other end of the connecting pipe penetrates through an installation box, a fan is fixedly arranged at the bottom of the inner cavity of the installation box, and one end of the fan is fixedly connected with the other end of the connecting pipe. A ventilation opening is arranged on one side of the installation box, and a dust-proof net is arranged in the inner cavity of the ventilation opening.

[0009] An intelligent bolt adaptive adjustment device for underground mines of the present invention for invention patent, wherein a box door is arranged on the surface of the installation box, and a handle is arranged on the surface of the box door.

[0010] An intelligent bolt adaptive adjustment device for underground mines of the present invention for invention patent, wherein an installation plate is arranged on one side of the installation box, and a humidity sensor and a temperature sensor are respectively arranged on one side of the installation plate and on one side of the installation box.

[0011] An intelligent bolt self - adaptive adjustment device for underground mines of the present invention for invention patent, wherein mounting blocks are provided on both sides of the mounting plate, and limiting screw holes are provided in the inner cavities of the two mounting blocks.

[0012] A method for adjusting an intelligent bolt self - adaptive adjustment device for underground mines of the present invention for invention patent, and the adjustment method is as follows: Step 1: After using a drill to drill a hole to the designed depth at the designed position of the surrounding rock, insert the outer rod and its internal components as a whole into the hole, and fix one end of the outer rod to the rock surface through an expansion bolt; Step 2: Input the initial pre - tightening force through the control terminal, apply the initial pre - tightening force through a hydraulic jack, and set the stress warning threshold and displacement threshold; Step 3: Real - time collect stress and displacement parameters through stress sensors and displacement sensors; Step 4: Threshold discrimination: If the displacement parameter > displacement threshold and the stress parameter < stress warning threshold, it is determined that fissure expansion occurs in the surrounding rock, the displacement sensor sends a signal to the controller, and the controller drives the driving motor to rotate forward to extend the inner rod, and at the same time the hydraulic pump automatically compensates the pressure; If the stress parameter > stress warning threshold and the displacement parameter < displacement threshold, it is determined that the surrounding rock is in the stage of compressive deformation, the stress sensor sends a signal to the controller, and the controller drives the driving motor to rotate in reverse to retract the inner rod, and at the same time the hydraulic pump relieves the pressure to avoid over - support.

[0013] Compared with the prior art, the beneficial effects of the present invention for invention patent are as follows: 1. By setting displacement sensors and stress sensors, the present invention for invention patent can collect stress and displacement parameter data in real - time, conduct threshold discrimination, and automatically adjust the support force according to the discrimination result and the cooperation of the driving component, timely adapt to the change of the mechanical state of the surrounding rock, effectively control the deformation of the surrounding rock, and improve the stability of the roadway.

[0014] 2. By setting a filter screen in the inner cavity of the second ventilation pipe, the present invention for invention patent can avoid dust and impurities from entering the inside of the outer rod through the second ventilation pipe, reducing the risk of dust and impurities eroding the internal components of the outer rod; By setting a heat dissipation component, the present invention for invention patent can dissipate heat from the internal components of the outer rod, increasing the stability of the internal components of the outer rod and avoiding the situation that the internal components of the outer rod malfunction due to overheating after long - term use; By setting the cooperation of the box door and the handle, the present invention for invention patent facilitates the staff to check and maintain the components in the installation box, thereby reducing the maintenance cost of the equipment; By setting humidity sensors and temperature sensors, the present invention for invention patent can monitor the temperature and humidity of the rock formation in real - time and adjust the support plan in time according to the monitoring results. Description of the Drawings

[0015] The accompanying drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings: Figure 1 is a schematic structural diagram of the present invention patent; Figure 2 is a schematic internal sectional structure diagram of the outer rod of the present invention patent; Figure 3 is a schematic structural diagram of the drive assembly of the present invention patent; Figure 4 is a schematic structural diagram of the heat dissipation assembly of the present invention patent; Figure 5 is a schematic internal structure diagram of the installation box of the present invention patent.

[0016] In the figure: 1. Outer rod; 2. Drive assembly; 201. Drive motor; 202. Transmission screw; 203. Screw sleeve; 204. Transmission block; 205. Transmission plate; 206. Slide block; 207. Inner rod; 208. Diffuse reflection coating; 209. Hydraulic pump; 210. Oil pipe; 211. Limit block; 3. Chute; 4. Displacement sensor; 5. Hydraulic jack; 6. Stress sensor; 7. Controller; 8. Heat dissipation assembly; 801. Connecting pipe; 802. Installation box; 803. Fan; 804. Ventilation opening; 805. Box door; 806. Handle; 9. Base plate; 10. First ventilation pipe; 11. Second ventilation pipe; 12. Screw; 13. Expansion bolt; 14. Installation plate; 15. Installation block; 16. Limit screw hole; 17. Humidity sensor; 18. Temperature sensor. Detailed implementation manners

[0017] The following will disclose multiple implementation manners of the present invention patent in the drawings. For the sake of clarity, many practical details will be described together in the following description. However, it should be understood that these practical details are not used to limit the present invention patent. That is to say, in some implementation manners of the present invention patent, these practical details are not necessary. In addition, for the purpose of simplifying the drawings, some conventional structures and components will be shown in the drawings in a simple schematic manner.

[0018] Please refer to Figures 1-5, an intelligent bolt adaptive adjustment device for underground mines in this invention patent includes an outer rod 1. A drive assembly 2 is provided inside the outer rod 1. The drive assembly 2 includes a drive motor 201 which is fixedly arranged at one end of the inner cavity of the outer rod 1. A transmission screw 202 is rotatably arranged at one end of the drive motor 201. A screw sleeve 203 is threadedly sleeved on the surface of the transmission screw 202. A transmission block 204 is fixedly sleeved on the surface of the screw sleeve 203. Transmission plates 205 are fixedly arranged on both sides of the transmission block 204. Sliders 206 are fixedly arranged on both sides of the transmission plates 205. And chutes 3 adapted to the sliders 206 are opened on both sides of the inner cavity of the outer rod 1. Inner rods 207 are fixedly arranged at one end of both transmission plates 205. Diffuse reflection coatings 208 are arranged on the surfaces of both inner rods 207. Displacement sensors 4 adapted to cooperate with the diffuse reflection coatings 208 are embedded on both sides of the inner cavity of the outer rod 1. A hydraulic jack 5 is fixedly connected to one end of both inner rods 207. A hydraulic pump 209 is fixedly arranged at one end of the inner cavity of the outer rod 1 and on the side of the drive motor 201. A hydraulic pipe 210 is fixedly arranged at one end of the hydraulic pump 209. And one end of the hydraulic pipe 210 is fixedly connected to the hydraulic jack 5. A limit block 211 is movably sleeved on the surface of the hydraulic pipe 210. And the limit block 211 is fixedly arranged in the inner cavity of the outer rod 1. One side of the limit block 211 is movably connected to one end of the transmission screw 202. A stress sensor 6 is embedded and installed on the inner wall of the outer rod 1. And the surface of the stress sensor 6 is sealed with epoxy resin. A controller 7 is fixedly arranged at one end of the inner cavity of the outer rod 1. And the displacement sensor 4, the stress sensor 6, the drive motor 201 and the hydraulic pump 209 are all electrically connected to the controller 7. A first ventilation pipe 10 and a second ventilation pipe 11 are symmetrically arranged in the inner cavity at one end of the outer rod 1. And a heat dissipation assembly 8 is connected to one end of the first ventilation pipe 10.

[0019] The initial pre-tightening force is input through the control terminal, and the initial pre-tightening force is applied by the hydraulic jack 5. The stress warning threshold and the displacement threshold are set. The stress and displacement parameters are collected in real time by the stress sensor 6 and the displacement sensor 4. If the displacement parameter > the displacement threshold and the stress parameter < the stress warning threshold, it is determined that the surrounding rock has crack expansion. The displacement sensor 4 sends a signal to the controller 7, and the controller 7 drives the driving motor 201 to operate. The driving motor 201 drives the transmission screw 202 to rotate. The transmission screw 202 drives the nut sleeve 203 to move. The nut sleeve 203 drives the transmission block 204 to move. The transmission block 204 drives the transmission plate 205 to move. The transmission plate 205 drives the inner rod 207 to elongate through the cooperation of the slider 206 and the chute 3. The elongation of the inner rod 207 drives the hydraulic jack 5 to elongate. At the same time, the hydraulic pump 209 supplements the pressure to increase the pre-tightening force and limit the further development of the crack. If the stress parameter > the stress warning threshold and the displacement parameter < the displacement threshold, it is determined that the surrounding rock is in the compression deformation stage. The stress sensor 6 sends a signal to the controller 7, and the controller 7 drives the driving motor 201 to reverse and retract the inner rod 207. At the same time, the hydraulic pump 209 relieves the pressure to release part of the stress and avoid overloading of the support.

[0020] One end of the outer rod 1 is provided with a screw rod 12, and a backing plate 9 and an expansion bolt 13 are respectively sleeved on the surface of the screw rod 12.

[0021] After using a drill to drill a hole in the surrounding rock at the designed position to the designed depth, the outer rod 1 and its internal components are integrally inserted into the hole, and one end of the outer rod 1 is fixed to the rock surface by the expansion bolt 13.

[0022] One ends of the first ventilation pipe 10 and the second ventilation pipe 11 both penetrate through the backing plate 9, and a filter screen is arranged in the inner cavity of the second ventilation pipe 11.

[0023] By arranging a filter screen in the inner cavity of the second ventilation pipe 11, it is possible to prevent dust and impurities from entering the inside of the outer rod 1 through the second ventilation pipe 11, reducing the risk of erosion of the internal components of the outer rod 1 by dust and impurities.

[0024] The heat dissipation component 8 includes a connecting pipe 801. One end of the connecting pipe 801 is fixedly connected to the first ventilation pipe 10. The other end of the connecting pipe 801 is provided with an installation box 802 in a penetrating manner. A fan 803 is fixedly arranged at the bottom of the inner cavity of the installation box 802, and one end of the fan 803 is fixedly connected to the other end of the connecting pipe 801. A ventilation port 804 is arranged on one side of the installation box 802, and a dust-proof net is arranged in the inner cavity of the ventilation port 804.

[0025] After the outer rod 1 is fixed, connect the connecting pipe 801 to the first vent 10. When dissipating heat from the internal components of the outer rod 1, the fan 803 is started, and air enters the inner cavity of the outer rod 1 through the connecting pipe 801 and the first ventilation pipe 10. By setting up the heat dissipation assembly 8, the internal components of the outer rod 1 can be cooled, increasing the stability of the internal components of the outer rod 1 and avoiding the situation of overheating and malfunction of the internal components of the outer rod 1 after long-term use.

[0026] The surface of the installation box 802 is provided with a box door 805, and the surface of the box door 805 is provided with a handle 806.

[0027] By setting the cooperation of the box door 805 and the handle 806, it is convenient for the staff to inspect and maintain the components in the installation box 802, thereby reducing the maintenance cost of the equipment.

[0028] One side of the installation box 802 is provided with a mounting plate 14, and a humidity sensor 17 and a temperature sensor 18 are respectively provided on one side of the mounting plate 14 and on one side of the installation box 802.

[0029] By setting the humidity sensor 17 and the temperature sensor 18, the temperature and humidity of the rock stratum can be monitored in real time, and the support plan can be adjusted in time according to the monitoring results. If the temperature and humidity are abnormal (such as a sudden increase in humidity indicating the risk of water damage), an alarm will be triggered and the current support parameters will be locked.

[0030] Both sides of the mounting plate 14 are provided with mounting blocks 15, and the inner cavities of the two mounting blocks 15 are both provided with limit screw holes 16.

[0031] After the heat dissipation assembly 8 is connected to the first ventilation pipe 10, the staff can use the limit screw rod to cooperate with the limit screw hole 16 to install the heat dissipation assembly 8, the humidity sensor 17 and the temperature sensor 18, which is convenient for the staff to use.

[0032] The adjustment method of an intelligent bolt self-adaptive adjustment device for underground mines of this invention patent is as follows: Step 1: After using a drill to drill a hole to the designed depth at the designed position of the surrounding rock, insert the outer rod 1 and its internal components as a whole into the hole, and fix one end of the outer rod 1 to the rock surface through the expansion bolt 13; Step 2: Input the initial pre-tightening force through the control terminal, apply the initial pre-tightening force through the hydraulic jack 5, and set the stress warning threshold and the displacement threshold; Step 3: Real-time collect stress and displacement parameters through the stress sensor 6 and the displacement sensor 4; Step 4: Threshold discrimination: If the displacement parameter > displacement threshold and the stress parameter < stress warning threshold, it is determined that the surrounding rock has crack expansion. The displacement sensor 4 sends a signal to the controller 7, and the controller 7 drives the driving motor 201 to rotate forward to extend the inner rod 207, and at the same time the hydraulic pump 209 automatically compensates the pressure. If the stress parameter > stress warning threshold and the displacement parameter < displacement threshold, it is determined that the surrounding rock is in the stage of compressive deformation. The stress sensor 6 sends a signal to the controller 7, and the controller 7 drives the driving motor 201 to rotate reversely to retract the inner rod 207, and at the same time the hydraulic pump 209 relieves the pressure to avoid overloading of the support.

[0033] When using this invention patent: After using a drill to drill a hole in the surrounding rock at the designed position to the designed depth, insert the outer rod 1 and its internal components as a whole into the hole, fix one end of the outer rod 1 to the rock surface through the expansion bolt 13, then connect the heat dissipation component 8 with the first ventilation pipe 10, and then install the heat dissipation component 8, the temperature sensor 17 and the humidity sensor 18 on the rock surface. Input the initial pre-tightening force through the control terminal, apply the initial pre-tightening force through the hydraulic jack 5, set the stress warning threshold and the displacement threshold, and collect the stress and displacement parameters in real time through the stress sensor 6 and the displacement sensor 4. If the displacement parameter > displacement threshold and the stress parameter < stress warning threshold, it is determined that the surrounding rock has crack expansion. The displacement sensor 4 sends a signal to the controller 7, and the controller 7 drives the driving motor 201 to rotate forward to extend the inner rod 207, and at the same time the hydraulic pump 209 automatically compensates the pressure. If the stress parameter > stress warning threshold and the displacement parameter < displacement threshold, it is determined that the surrounding rock is in the stage of compressive deformation. The stress sensor 6 sends a signal to the controller 7, and the controller 7 drives the driving motor 201 to rotate reversely to retract the inner rod 207, and at the same time the hydraulic pump 209 relieves the pressure to avoid overloading of the support.

[0034] The above is only the implementation manner of this invention patent and is not used to limit this invention patent. For those skilled in the art, various changes and modifications can be made to this invention patent. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this invention patent shall be included within the scope of the claims of this invention patent.

Claims

1. An intelligent bolt adaptive adjustment device for underground mines, including an outer rod (1), characterized in that: The interior of the outer rod (1) is provided with a driving assembly (2). The driving assembly (2) includes a driving motor (201). The driving motor (201) is fixedly arranged at one end of the inner cavity of the outer rod (1). One end of the driving motor (201) is rotatably provided with a transmission screw rod (202). A screw sleeve (203) is threadedly sleeved on the surface of the transmission screw rod (202). A transmission block (204) is fixedly sleeved on the surface of the screw sleeve (203). Transmission plates (205) are fixedly arranged on both sides of the transmission block (204). Sliders (206) are fixedly arranged on both sides of the transmission plate (205). Chutes (3) adapted to the sliders (206) are opened on both sides of the inner cavity of the outer rod (1). Inner rods (207) are fixedly arranged at one end of both transmission plates (206). Diffuse reflection coatings (208) are arranged on the surfaces of both inner rods (207). Displacement sensors (4) adapted to the diffuse reflection coatings (208) are embedded on both sides of the inner cavity of the outer rod (1). One end of both inner rods (207) is fixedly connected to a hydraulic jack (5). A hydraulic pump (209) is fixedly arranged at one end of the inner cavity of the outer rod (1) and on one side of the driving motor (201). One end of the hydraulic pump (209) is fixedly provided with an oil pipe (210). One end of the oil pipe (210) is fixedly connected to the hydraulic jack (5). A limit block (211) is movably sleeved on the surface of the oil pipe (211). The limit block (211) is fixedly arranged in the inner cavity of the outer rod (1). One side of the limit block (211) is movably connected to one end of the transmission screw rod (202). A stress sensor (6) is embedded and installed on the inner wall of the outer rod (1). A controller (7) is fixedly arranged at one end of the inner cavity of the outer rod (1). The displacement sensor (4), the stress sensor (6), the driving motor (201), and the hydraulic pump (209) are all electrically connected to the controller (7). A first ventilation pipe (10) and a second ventilation pipe (11) are symmetrically arranged at one end of the inner cavity of the outer rod (1). One end of the first ventilation pipe (10) is connected to a heat dissipation assembly (8).

2. The intelligent bolt adaptive adjustment device for underground mines according to claim 1, characterized in that: One end of the outer rod (1) is provided with a screw rod (12). A backing plate (9) and an expansion bolt (13) are respectively sleeved on the surface of the screw rod (12).

3. An intelligent bolt self - adaptive adjustment device for underground mines according to claim 1, characterized in that: One ends of the first ventilation pipe (10) and the second ventilation pipe (11) both penetrate through the backing plate (9). A filter screen is arranged in the inner cavity of the second ventilation pipe (11).

4. An intelligent bolt adaptive adjustment device for underground mines according to claim 1, characterized in that: The heat dissipation assembly (8) includes a connecting pipe (801). One end of the connecting pipe (801) is fixedly connected to the first ventilation pipe (10). The other end of the connecting pipe (801) penetrates through an installation box (802). A fan (803) is fixedly arranged at the bottom of the inner cavity of the installation box (802). One end of the fan (803) is fixedly connected to the other end of the connecting pipe (801). A ventilation opening (804) is arranged on one side of the installation box (802). A dustproof net is arranged in the inner cavity of the ventilation opening (804).

5. An intelligent bolt self - adaptive adjustment device for underground mines according to claim 4, characterized in that: The surface of the installation box (802) is provided with a box door (805), and the surface of the box door (805) is provided with a handle (806).

6. The intelligent bolt adaptive adjustment device for underground mines according to claim 4, characterized in that: One side of the installation box (802) is provided with a mounting plate (14). A humidity sensor (17) and a temperature sensor (18) are respectively provided on one side of the mounting plate (14) and on one side of the installation box (802).

7. An intelligent bolt self-adaptive adjustment device for underground mines according to claim 6, characterized in that: Mounting blocks (15) are provided on both sides of the mounting plate (14), and limiting screw holes (16) are provided in the inner cavities of the two mounting blocks (15).

8. An adjustment method for an intelligent bolt adaptive adjustment device in an underground mine, and the adjustment method is as follows: Step 1: After using a drill to drill a hole to the designed depth at the designed position of the surrounding rock, insert the outer rod (1) and its internal components as a whole into the hole, and fix one end of the outer rod (1) to the rock surface through an expansion bolt (13). Step 2: Input an initial pre-tightening force through a control terminal, apply the initial pre-tightening force through a hydraulic jack (5), and set a stress warning threshold and a displacement threshold. Step 3: Real-time collect stress and displacement parameters through a stress sensor (6) and a displacement sensor (4). Step 4: Threshold discrimination: If the displacement parameter > the displacement threshold and the stress parameter < the stress warning threshold, it is determined that a crack has expanded in the surrounding rock. The displacement sensor (4) sends a signal to the controller (7), and the controller (7) drives the driving motor (201) to rotate forward to extend the inner rod (207), and at the same time, the hydraulic pump (209) automatically makes up the pressure. If the stress parameter > the stress warning threshold and the displacement parameter < the displacement threshold, it is determined that the surrounding rock is in the stage of compressive deformation. The stress sensor (6) sends a signal to the controller (7), and the controller (7) drives the driving motor (201) to rotate reversely to retract the inner rod (207), and at the same time, the hydraulic pump (209) relieves the pressure to avoid overloading of the support.

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